One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,14,20,15,19,13,17)(11,21,24,30,25,16,23,32)(12,18,27,35,28,36,29,33)(22,37,26,40,38,31,39,34)(1,2)(3,6)(4,5)(7,8)(9,11,15,25)(10,16,19,21)(12,26,28,39)(13,24,14,23)(17,32,20,30)(18,34,36,40)(22,29,38,27)(31,33,37,35)(2,5)(6,8)(10,17,19,20)(16,30,21,32)(18,35,36,33)(31,34,37,40)(1,3,4,7)(2,6,5,8)(9,12)(10,18)(11,22)(13,29)(14,27)(15,28)(16,31)(17,33)(19,36)(20,35)(21,37)(23,39)(24,26)(25,38)(30,40)(32,34)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.